Tumor cells that disseminate to the bone marrow (disseminated tumor cells [DTCs]) have been identified in 30% of patients with stage I through II breast cancer (BC) and predict outcome. Neoadjuvant chemotherapy (NACT) is effective in reducing the size of primary tumors or eradicating lymph node metastases before surgery, but little is known regarding the presence or significance of DTCs after NACT.
The authors evaluated DTCs in 95 patients with clinical stage I through III BC. Bone marrow samples were collected after completion of NACT at the time they underwent surgery for primary BC. DTCs were assessed using an anticytokeratin antibody cocktail. Primary tumor markers, the extent of lymph node (LN) involvement, they type of NACT administered, and response to NACT were compared with presence of DTCs. Chi-square and Fisher exact tests were used for statistical analyses.
The median patient age at diagnosis was 51 years, and the median follow-up was 24 months. Forty-six percent of patients had tumors classified as T1/T2, 20% had T3 tumors, 34.5% had T4 tumors, and 81% had lymph node metastasis before NACT. DTCs were identified in 26% of patients after NACT. No associations were observed between DTCs and primary tumor characteristics or LN involvement. A pathologic complete response was observed in 25 patients (26%) but was not predictive of DTCs after NACT (P = .83). DTCs after NACT predicted worse BC-specific survival (P < .02).
The presence of DTCs was an independent predictor of outcome after NACT. The current results indicated that monitoring hematogenous micrometastatic disease after NACT may be useful in selecting patients who might benefit from additional systemic adjuvant therapies.